The objectives of this project are to conduct 13-Week Prechronic studies of 1,1,1-Trichloroethane by the dosed feed route of administration using microencapsulated chemical. Groups of male and female F344/N rats and B6C3F1 mice shall receive 1 of 5 dose levels or the vehicle for 13-weeks, Ten additional male and female rats shall be treated for 21 days for hematology and clinical chemistry evaluations at days 4 and 21. On day 21 all the additional rats except 5 male rats from the additional high, middle, low, and control groups shall be sacrificed without a necropsy. The remaining additional male rats shall continue treatment until day 84 for urinary metabolite analyses at days 28 and 84. The core study rats shall be evaluated for hematology and clinical chemistries at study termination. In addition, Sperm Morphology and Vaginal Cytology Evaluations (SMVCE) shall be conducted on rats and mice just prior to study termination. Blood smears shall be obtained from mice at termination for an evaluation of micronuclei.